TITLE: Paying Attention to the Details
AUTHOR: Eugene Wallingford
DATE: September 16, 2004  4:01 PM
DESC: risk is a combination of factors -- attend to those, too
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BODY:
At PLoP last week Gerard Meszaros said something that caught my ear:

<BLOCKQUOTE>
risk = probability X consequence

Why waste energy minimizing a risk whose consequence is too low
to be worth the effort?
</BLOCKQUOTE>

This idea came up later at the conference when Ward talked
about the
<A HREF="http://www.cs.uni.edu/~wallingf/blog/archives/monthly/2004-09.html#e2004-09-15T11_33_28.htm">
   convention-busting assumption of wiki</A>,
but it is of course a central tenet in the agile methods.  Too
often, when faced with an undesirable potential result, we focus
too quickly on the event's likelihood, or on its effects.  But
risk arises in the interplay between the two, not in either
factor alone.  If an event is likely to happen but has only a
small negative effect, or if it has a major effect but is unlikely
to occur, then our risk is mitigated by the second factor.
Recognizing this can help us avoid the pitfall of running from
a potential event for the wrong reasons.

Recognizing this relationship can also help us to take control
of the problem.  In XP and the other agile methods, we accept
that change is highly likely, so we work to minimize the consequence
of change.  We do that by maintaining a comprehensive suite of
tests to help us verify that changes to the system don't break
something unexpectedly; and, when they do, we use the tests to
find and fix the problem spots.  We minimize the consequence of
change by using refactoring tools that help us to change the
structure of our programs when design requirements call for something
different.  We minimize the consequence of change by working on
short iterations, continuously integrating our code, and releasing
versions frequently, because these disciplines ensure that we
get feedback from our tools and client frequently.

Learning to pay attention to all the variables in a situation
is more general than just assessing risk.  In a
<A HREF="http://groups.yahoo.com/group/extremeprogramming/message/96294">
   recent message</A>
to the XP mailing list, Kent Beck said that he tries to help his
customers to think in terms of return, not just value or cost:

<BLOCKQUOTE>
I have another goal for early estimation, which is to encourage the
business-decision-makers to focus on return instead of just value.
If the choice is between the Yugo and the Ferrari, I'll take the
Ferrari every time. If I have $6000 and I know the price of the
two cars, my thinking is more realistic.
</BLOCKQUOTE>

A system's value is a function of many variables, including its
features, its cost, and the environment in which it must operate.

We can become more accurate, more efficient decision makers by
paying attention to what really matters, and not being distracted
by our biases and initial reactions.  Often, these biases were
learned in other times, other environments.  Fortunately, I think
that this is something that we can <I>learn</I> to do, by consciously
developing new habits of thought.  It takes discipline and patience
to form new habits, but the payoff is often worth the effort.
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